1. Field of the Invention
The present invention relates to printed circuit board connectors. The present invention particularly relates to a printed circuit board connector structure to which a plurality of contact leads can be securely solder-bonded to a printed circuit board surface.
2. Related Art
A shell formed by a metallic plate composes an outer shell of a connector on a printed circuit board connector, for example. A part of the shell is solder-bonded to a surface of the printed circuit board as a reinforcing tab extending from the outer shell to improve connector strength.
However, in a plan view, this kind of reinforcing tab extends outward from the connector shell occupying a certain amount installation space on the printed circuit board. This causes a problem of reduced space for mounting other electronic components.
To resolve this kind of problem, a printed circuit board connector was disclosed in Japanese unexamined patent publication 2001-35603 (hereinafter referred to as pat. pub. 1) that was compact and achieved a reduced height, reduced connector occupying space at a mounting surface of the printed circuit board, and ensured connector strength.
FIG. 16 is an exploded perspective assembly view of the printed circuit board connector described in pat. pub. 1, showing the housing and contacts opposingly disposed. FIG. 16 in this application corresponds to FIG. 3 of pat. pub. 1.
The following refers to FIG. 16. The printed circuit board connector 90 (hereinafter referred to as the connector) according to pat. pub. 1 is equipped with insulated housing 7, and a plurality of contacts 9. The housing 7 includes a back-wall portion 71 and a pair of side-wall portions 72, 72. A plurality of contact insertion holes 71a is formed in the back-wall portion 71 along a length direction thereof. The pair of side-wall portions 72, 72 extends from both ends of the back-wall portion 71 toward a forward direction. The plurality of contacts 9 is press-fitted into the contact insertion holes 71a in the housing 7.
Furthermore, as shown in FIG. 16, the contact 9 includes a lead portion 9b bent substantially to a right angle extends parallel to a contact-connecting portion 9a and in a direction opposite to the contact-connecting portion 9a from the back-wall portion 71. The lead portion 9b is solder-bonded to a surface (mounting surface) of the printed circuit board, not shown. That is to say, the connector 90 is a surface-mount type printed circuit board connector.
The following refers to FIG. 16. The drawing clearly shows that a width of the contact-connecting portion 9a base-end portion is wider than a leading end portion side thereof. Also, a pair or barbs 9c, 9c is formed at the base-end portion of the contact-connecting portions 9a. The contact 9 is inserted until shoulders 9s disposed at the base-end portion of the contact-connecting portion 9a abut a back of the contact insertion hole 71a. While the contact 9 is being inserted, the pair of barbs 9c, 9c bite into the inner walls while scraping along an inner wall of the contact insertion holes 71a, thereby securely fastening the contact 9 in the housing 7.
The following refers to FIG. 16. It is easy precisely to form a pitch between electrodes on the contact 9 or the contact insertion hole 71a. However, because the housing 7 is formed from plastic, thermal strain can causes warping in a length direction of the back-wall portion 71. For that reason, there is a problem that co-planarity cannot be ensured for the solder joint surfaces of the plurality of lead portions 9b. 
Conversely, while it is possible to correct the plurality of lead portions 9b to ensure predetermined co-planarity for these solder-bonded surfaces, printed circuit board warping still sometimes occurs. Therefore, while the plurality of lead portions 9b may be in contact with the printed circuit board surface at both end portions, for example, there is a problem in that the lead portions 9b may become slightly separated from the printed circuit board surface at a central portion if warping occurs, for example. This makes it difficult to obtain a uniform solder thickness.